| BMW Engine >> REVISED CYL HEAD MOUNTING COMPONENTS & PROC |
Revised Cylinder Head Mounting Components and Procedures on
BMW 1983-86 325e and 528e (VIN M20B25 and M20B27) Engines
AERA has received many calls on leaks of the cylinder head to block joint and cylinder head bolt breakage on BMW M20 series engines (applicable to all displacements). The following revised components and procedures should eliminate these difficulties for AERA members and their customers.
A revised cylinder head gasket with improved sealing should eliminate oil seepage between cylinders No. 3 and 4 on the exhaust side of the engine. A .012 (.3mm) thicker head gasket should be used when cylinder block deck height or cylinder head minimum thickness specifications are exceeded.
Previous Head Gasket 11 12 1 278 305
Standard Head Gasket 11 12 1 708 891
Oversize Head Gasket 11 12 1 713 493
Revised cylinder head bolts of increased strength and hardness along with a new torque procedure should further reduce head gasket problems. The revised cylinder head bolts are easily identified by their Torx heads and black finish. BMW recommends installation of the revised bolt whenever the cylinder
head is serviced. Bolts should be replaced as a complete set available under the Part #11 12 1 726 478 (14 bolts).
Use the following torque procedure on the revised bolts:
1) Torque all bolts to 22 lbs.ft. (30 Nm)
2) Turn all bolts 90^
3) Turn all bolts an additional 90^
The waiting and running time requirements used with previous procedures no longer apply.
The AERA Technical Committee
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